Grate-bar



(N9 Model.)

W. U. PAIRBAIRN.

' Grate Bar. No .24l,639.

Patented May 17, I881.

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N. PETERS. Phnwumu n mr, Wm!

UNITED STATES PATENT OFF-ICE.

WILLIAM U. FAIRBAIRN, OF BOSTON, MASSACHUSETTS.

GRATE-BA'R.

SPECIFICATION forming part of Letters Patent No. 241,639, dated May 17,1881.

Application filed March 21, 1881.

.To all whom it may concern:

Be it known that I, WILLIAMU. FAIRBAIRN, of Boston, in the countyofSuffolk and State of Massachusetts, have invented certain new and usefulImprovements in Grate-Bars. of which the following is a full, clear, andaccurate description, reference being had to the accompanying drawings,forming a part of this specification in explaining its nature, in which-Figure 1 is a perspective of a grate-bar illustratin g my invention,with a portion of its web broken outto show the interior of the bar.Fig. 2 is a front elevation. Fig. 3 is aview in perspective, enlarged,of the rear part of the bar.

Figs. 4 and 5 are views representing a modification in construction,hereinafter more fully described.

This invention is an improvement upon that describedin my applicationfor Letters Patent filed August 7, 1880. In that application I havedescribed a grate-bar having end supports for suspending it in thefurnace, and a hollow web within and below said supports, having anopening at its front end, which is some little distance back from thefront end of the bar, being closed at its rear and opening on one orboth sides near the rear, whereby air may be drawn from the ash-pitthrough the bar by the action of the fire to the rear of the fire,thereby providing for a suficient supply of oxygen to properly supportthe combustion at that part of the furnace.

I have found in the practical working of my invention that owing to therapidity with which the air is drawn through the bar insome instances itis desirable to check its flow some during its passage through the bar,as by so doing the air is more heated in passingthrough the bar thanotherwise would be the case. I have also found that it is advantageousto build a narrow hood or projection over the exits to prevent ashesfrom falling into and clogging them or the passage within the bar, alsoto extend the mouth or opening to the passagefo the end of the bar.

A is the bar. It has afire-supportin g surface, a, the end supports, a,the web a within and below the end supports, and the passage a in theweb, having an opening, a", extending from the bottom of the webupwardly and outwardly to the end of the bar, forming the narrow pas-(No model.)

sage a in the front end support. 'The web is closed at its rear end, andhas one or more openings, a, in one or both sides, at or near the rearand near the fire-supporting surface.

a" is a hood or projecting portion of the bar over each exit, preferablyof the same length, and slanting outwardly and downwardly from thefire-supportin g surface, so as not to increase its width materially,while it acts as a fender in preventing ashes from lodging in theexitpassage.

a are lugs, which project horizontally from the bar and serve tomaintain it in position in relation to its companion bars by coming incontact with the like lugs thereon.

To check the flow of air through the passage a and thereby to heat it, anumber of devices can be employed, and among them I mention the use ofasbestus or other non-combustible material packed lightly in thepassage, through which, however, air can be drawn. Wire-gauze, in one ormore layers extending from side to side of the bar to retard the passageof air, will answer the purposes of this portion of the invention, or acentral plate or partition for diminishing the volume of air bydecreasing the size of the passage will perform the same effect. By thisconstruction the air is not only retarded, but heated more readily, onaccount of its volume being thin and the heat-radiatin g surfaces of thebar being increased.

One form of the partition-bar is shown in Fig. 4, the partition-platebeing cast with the remainder ofthe bar. The division-plate, however,may be made separate and inserted into a groove in the bar, as shown inFig. 5. Any other suitable means for accomplishing this de vice may beemployed.

It will be observedthat is, in my invention already described-the web ispractically suspended in the ash-pit chamber, so that the passagetherein is most advantageously located for receiving air, and that,also, the location of the mouth of the passage in the ash-pit is thatbest adapted for the purpose, being arranged, when the baris in positionin the furnace, across the line of the principal part of the current ofair from the ash-pit door to the fire.

Having thus fully described my invention, I claim and desire to secureby Letters Patent A of the United States-- Ind to opening at the frontend of the bar, and upon one or both sides near the rear, thecombination of such passage with means, substantially.

as described, for checking or retarding the flow of air in said passage,all as and for the purposes described.

WM. U. FAIRBAIRN. Witnesses:

A. J. OETTINGER, W. O. Foes.

